Toy vehicle adapted for running on rails and a toy construction system

A toy vehicle configured for running on rails, the toy vehicle comprises a chassis comprising:

• a first end and a second end, two side faces extending in a longitudinal direction of the toy vehicle and a top portion, the toy vehicle comprising at least two axles, said at least two axles comprising a wheel, and where the chassis comprises oblong recesses positioned on an inner surface of the chassis, the oblong recesses adapted to obtain a protrusion of a wheel or an end portion of the at least two axles, the chassis comprising an axle support arm positioned centrally between two wheels on each of the at least two axles and flexibly supporting each of the at least two axles, wherein each axle support arm includes a void configured to receive one of the two or mroe axles and to allow angular movement of each of the two or more axles within the void, wherein the wheels are slidable within the oblong recesses but to avoid disengagement between an oblong recess and the protrusion of a wheel or an end portion of the at least two axles, respectively, and wherein each axle support arm only adds friction to the axles when it is necessary to keep the wheels in place and to avoid detachment.